Flywheels are used with various types of motor-driven equipment. Their primary purpose is to provide an opposing and moderating force by its inertia to any fluctuation of speed in the machinery which it revolves. Some flywheels have integral vanes or blades to produce air flow through the motor assembly that rotates the flywheel. But if the integral vanes are improperly configured they may generate excessive noise. Indeed, motor applications may utilize a flywheel that has an open-vane design which allows the air to roll off the vane axially as the flywheel rotates causing turbulence and resulting in excessive noise. Most of the air that starts at the inner diameter of the vanes never makes it to the exhaust tip of the blades and as such, this type of design is considered to be very inefficient. Moreover, since there is no ring closing the front area of the fan, there is no capacity or ability to incorporate an eye seal.
One attempt at improving a flywheel assembly is disclosed in U.S. Pat. No. 6,695,581. This patent discloses a fan-flywheel-pulley assembly used in conjunction with an electric motor. The pulley extends axially from the flywheel and drives a belt as is commonly used on treadmill exercise equipment. The flywheel includes an outer circumferential flywheel surface partially forming a plurality of circumferentially spaced openings. The flywheel may include a baffle that extends circumferentially and in close proximity to a cylindrical wall unit of the motor from an inner diameter to an outer diameter to limit a gap between the baffle and the cylindrical wall unit. This assembly may also include a radial fan disposed within the flywheel including a plurality of blades extending at least from the flywheel inner diameter to the outer diameter, wherein each opening is positioned between each adjacent fan blade. This patent also discloses that the pulley, the flywheel, and the radial fan may be integrally formed.
Although this disclosed configuration is an improvement in the art, it is believed that configuring the flywheel to surround the motor housing with the radial fan disposed away from the motor housing still allows for air flow inefficiencies. It is believed that this is a result of the cooling air having to travel a further distance through the flywheel assembly. Moreover, the gap between the baffle and the motor housing allows for “parasitic” airflow which generates noise and reduces fan efficiency. In addition, the gap between the baffle and the motor housing allows for internal fan noise to be emitted therefrom.
Yet a further drawback of the known flywheel motor assemblies is attributed to the imbalance problems in coupling the flywheel to the motor's rotatable shaft. When the flywheel is in an imbalance condition, undue stress is placed on the motor during operation and after a period of time, causes excessive wear on the motor and generates vibration. This generates additional noise and, of course, adversely effects the operation of the associated machinery. Indeed, it is believed that the shaft configuration of known assemblies does not sufficiently control flywheel positioning after assembly. In most assemblies, the flywheel is contained axially by seating against a small annular ring on the shaft face. This configuration is believed to be insufficient for controlling and maintaining radial alignment. In order to overcome this system imbalance after assembly, the flywheel motor assembly must undergo a final balancing operation. As will be appreciated, this is a time-consuming operation and does not always ensure that a balanced condition is obtained.
Therefore, there is a need in the art for a more efficient flywheel/fan assembly that improves air flow through a motor housing, reduces noise and also provides improved balance quality.